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1.
Medicina (Kaunas) ; 60(6)2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38929479

RESUMO

Background and Objectives: Non-alcoholic fatty liver disease (NAFLD) is associated with obesity and ranges from simple steatosis to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. Accumulating evidence in animal models suggests that loss of interleukin-10 (IL-10) anti-inflammatory actions might contribute to lobular inflammation, considered one of the first steps toward NASH development. However, the role of IL-10 in lobular inflammation remains poorly explored in humans. We examined mRNA and protein levels of IL-10 in liver biopsies and serum samples from morbidly obese patients, investigating the relationship between IL-10 and lobular inflammation degree. Materials and Methods: We prospectively enrolled morbidly obese patients of both sexes, assessing the lobular inflammation grade by the Brunt scoring system to categorize participants into mild (n = 7), moderate (n = 19), or severe (n = 13) lobular inflammation groups. We quantified the hepatic mRNA expression of IL-10 by quantitative polymerase chain reaction and protein IL-10 levels in liver and serum samples by Luminex Assay. We estimated statistical differences by one-way analysis of variance (ANOVA) and Tukey's multiple comparison test. Results: The hepatic expression of IL-10 significantly diminished in patients with severe lobular inflammation compared with the moderate lobular inflammation group (p = 0.01). The hepatic IL-10 protein levels decreased in patients with moderate or severe lobular inflammation compared with the mild lobular inflammation group (p = 0.008 and p = 0.0008, respectively). In circulation, IL-10 also significantly decreased in subjects with moderate or severe lobular inflammation compared with the mild lobular inflammation group (p = 0.005 and p < 0.0001, respectively). Conclusions: In liver biopsies and serum samples of morbidly obese patients, the protein levels of IL-10 progressively decrease as lobular inflammation increases, supporting the hypothesis that lobular inflammation develops because of the loss of the IL-10-mediated anti-inflammatory counterbalance.


Assuntos
Inflamação , Interleucina-10 , Fígado , Obesidade Mórbida , Humanos , Interleucina-10/sangue , Interleucina-10/análise , Obesidade Mórbida/complicações , Obesidade Mórbida/sangue , Feminino , Masculino , Adulto , Pessoa de Meia-Idade , Fígado/metabolismo , Fígado/patologia , Estudos Prospectivos , Inflamação/sangue , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/complicações
2.
Bone Rep ; 21: 101766, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38681748

RESUMO

Osteogenesis imperfecta (OI) is a rare hereditary disorder characterized by bone fragility and frequent fractures. While most cases are attributed to variations in collagen-coding genes COL1A1 and COL1A2, other genes such as IFITM5 have also been associated with the disease, accounting for up to 5 % of cases. Here, we report a case of a 3-month-old female with a femur fracture and limb deformity. X-rays revealed evidence of osteopenia and previous fractures in the arms, clavicle, ribs, and left limb, alongside prenatal bone deformities detected by ultrasound. Initial clinical evaluation suggested progressively deforming (Sillence's type III) osteogenesis imperfecta (OI). Molecular testing led to the diagnosis of IFITM5-related OI, identifying the c.-14C>T (rs587776916) variant. Although this variant has been previously reported in patients with IFITM5-related OI, prenatal involvement had not been associated with this variant.

3.
Transplant Proc ; 52(4): 1127-1131, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32307138

RESUMO

The main complication associated with renal graft loss is immune rejection. The gold standard for the diagnosis of renal graft rejection is percutaneous renal biopsy, which is expensive and can lead to complications. Inflammation is one of the main pathogenic pathways in allograft rejection, and urine samples seem to be efficient windows to explore the allograft condition with a high cost-benefit ratio. This study aimed to evaluate the messenger ribonucleic acid (mRNA) profile expression pattern for interleukin (IL) 2, IL-4, IL-6, IL-8, and IL-10; tumor necrosis factor alfa; gamma interferon; and transforming growth factor ß1 in the urine renal cells of patients with a diagnosis of humoral rejection and patients with a diagnosis of normal biopsy. METHODS: An observational, cross-sectional analytical study was performed. All kidney transplants were performed at the Organ Transplant Department between 2018 and 2019. Also, a healthy control with a normal blood test and no apparent infection was included. mRNA from urine samples and biopsies was isolated, and the expression of interleukins was analyzed in PCR real time. Data were analyzed by Shapiro-Wilk and Kruskal-Wallis tests. RESULTS: The proinflammatory IL expression pattern in urine samples of kidney rejection group showed overexpression for IL-8 (P = .0001). No differences were observed in the rest of the interleukins analyzed. When we compared the results in the rejected versus not rejected transplanted patients with a group of apparently healthy subjects, the difference remains consistent. Thus, mRNA of IL-8 could function as a diagnostic tool in cases of chronic damage secondary to fibrosis.


Assuntos
Biomarcadores/urina , Rejeição de Enxerto/urina , Interleucina-8/urina , Transplante de Rim/efeitos adversos , Adulto , Estudos Transversais , Feminino , Rejeição de Enxerto/diagnóstico , Rejeição de Enxerto/imunologia , Humanos , Interleucina-8/imunologia , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Transplante Homólogo
4.
Transplant Proc ; 52(4): 1132-1135, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32249055

RESUMO

Kidney transplant (KT) is the first therapeutic option for most patients with chronic renal failure that requires renal function replacement. The main complication associated with renal graft loss is immune rejection. The T regulatory pathways play a key role in this process, and abnormalities in some of these molecules could participate in the graft rejection. In this paper, our group performed an exploratory analysis of the behavior of the coinducible molecules (CD28, CTLA-4, ICOS, PD-1) in patients with KT rejection and control KT patients without rejection. The Mann-Whitney U test, used for 2 groups, showed significant differences (P = .0005), indicating that PD-1 is underexpressed in patients with allograft rejection. No differences were found in CD28+, regulatory T cells (T reg), CTLA-4, and ICOS, so we are proposing that PD-1 is a key player in the immunotolerance phenomenon and its underexpression participates in the rejection process. More research needs to be performed on this topic.


Assuntos
Rejeição de Enxerto/imunologia , Transplante de Rim , Receptor de Morte Celular Programada 1/imunologia , Imunologia de Transplantes/imunologia , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Linfócitos T Reguladores/imunologia , Transplante Homólogo
5.
Pathol Oncol Res ; 25(3): 1233-1243, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30759303

RESUMO

Epidemiological evidence points to a link between insulin resistance (IR) and breast cancer (BrCA). Insulin plays a role in CD8+ T cells (CD8T) differentiation and function and affects adipocytokines levels. CD8T activity in BrCA is associated with favorable outcome; while PD1 and TIM3 are markers of CD8T exhaustion and play critical roles in the negative regulation of T cell responses. Patients with (BrCA) have high expression levels of PD1 on circulating. Therefore, we hypothesized that BrCA and IR could affect PD1 and/or TIM3 expression on circulating CD8T. We determine PD1 and TIM3 expression on CD8T and analyze the relationship of CD8T phenotype with serum insulin and plasma adipocytokines levels in the different groups. We enrolled four groups of treatment-naive patients: women without neoplasms (Neo-)/without IR (IR-), Neo-/with IR (IR+), BrCa/IR- and BrCa/IR+. We found interactions between BrCA and IR with respect to TIM3 on naïve and central memory (CM) CD8T subsets. Furthermore, BrCA had a greater PD1 + TIM3- CD8T frequency in CD8T subsets than Neo-. IR+ presented a significantly lower PD1 + TIM3- frequency in CD8T subsets compare to Non-IR. In addition, we found a negative correlation between insulin levels, HOMA and frequency of PD1 + TIM3- in CD8T and a positive correlation between adiponectin levels and the frequency PD1 + TIM3- in CD8T. The increased expression of PD1 on different subsets of CD8T from BrCa patients is consistent with immunological tolerance, whereas IR has a contrary effect. IR could have a deleterious role in the activation of CD8T that can be relevant to new BrCa immunotherapy.


Assuntos
Neoplasias da Mama/metabolismo , Linfócitos T CD8-Positivos/imunologia , Carcinoma Ductal de Mama/metabolismo , Carcinoma Lobular/metabolismo , Receptor Celular 2 do Vírus da Hepatite A/metabolismo , Resistência à Insulina , Receptor de Morte Celular Programada 1/metabolismo , Adiponectina/metabolismo , Neoplasias da Mama/sangue , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Linfócitos T CD8-Positivos/metabolismo , Carcinoma Ductal de Mama/sangue , Carcinoma Ductal de Mama/imunologia , Carcinoma Ductal de Mama/patologia , Carcinoma Lobular/sangue , Carcinoma Lobular/imunologia , Carcinoma Lobular/patologia , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Prognóstico
6.
J Clin Endocrinol Metab ; 102(1): 132-140, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27778642

RESUMO

Context: Insulin resistance precedes metabolic syndrome abnormalities and may promote cardiovascular disease and type 2 diabetes in children with obesity. Results of lifestyle modification programs have been discouraging, and the use of adjuvant strategies has been necessary. Objective: This study aimed to evaluate the effects of metformin and conjugated linoleic acid (CLA) on insulin sensitivity, measured via euglycemic-hyperinsulinemic clamp technique and insulin pathway expression molecules in muscle biopsies of children with obesity. Design: A randomized, double-blinded, placebo-controlled clinical trial was conducted. Setting: Children with obesity were randomly assigned to receive metformin, CLA, or placebo. Results: Intervention had a positive effect in all groups. For insulin sensitivity Rd value (mg/kg/min), there was a statistically significant difference between the CLA vs placebo (6.53 ± 2.54 vs 5.05 ± 1.46, P = 0.035). Insulinemia and homeostatic model assessment of insulin resistance significantly improved in the CLA group (P = 0.045). After analysis of covariance was performed and the influence of body mass index, age, Tanner stage, prescribed diet, and fitness achievement was controlled, a clinically relevant effect size on insulin sensitivity remained evident in the CLA group (37%) and exceeded lifestyle program benefits. Moreover, upregulated expression of the insulin receptor substrate 2 was evident in muscle biopsies of the CLA group. Conclusions: Improvement of insulin sensitivity, measured via euglycemic-hyperinsulinemic clamp and IRS2 upregulation, favored patients treated with CLA.


Assuntos
Doenças Cardiovasculares/prevenção & controle , Hipoglicemiantes/uso terapêutico , Resistência à Insulina , Ácidos Linoleicos Conjugados/uso terapêutico , Síndrome Metabólica/prevenção & controle , Metformina/uso terapêutico , Obesidade/tratamento farmacológico , Adolescente , Biomarcadores/análise , Glicemia/análise , Composição Corporal , Criança , Método Duplo-Cego , Quimioterapia Combinada , Feminino , Seguimentos , Humanos , Insulina/sangue , Lipídeos/análise , Masculino , Obesidade/complicações , Prognóstico
7.
Sci Rep ; 6: 34504, 2016 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-27703260

RESUMO

Deregulated expression of microRNAs has been associated with angiogenesis. Studying the miRNome of locally advanced breast tumors we unsuspectedly found a dramatically repression of miR-204, a small non-coding RNA with no previous involvement in tumor angiogenesis. Downregulation of miR-204 was confirmed in an independent cohort of patients and breast cancer cell lines. Gain-of-function analysis indicates that ectopic expression of miR-204 impairs cell proliferation, anchorage-independent growth, migration, invasion, and the formation of 3D capillary networks in vitro. Likewise, in vivo vascularization and angiogenesis were suppressed by miR-204 in a nu/nu mice model. Genome-wide profiling of MDA-MB-231 cells expressing miR-204 revealed changes in the expression of hundred cancer-related genes. Of these, we focused on the study of pro-angiogenic ANGPT1 and TGFßR2. Functional analysis using luciferase reporter and rescue assays confirmed that ANGPT1 and TGFßR2 are novel effectors downstream of miR-204. Accordingly, an inverse correlation between miR-204 and ANGPT1/TGFßR2 expression was found in breast tumors. Knockdown of TGFßR2, but not ANGPT1, impairs cell proliferation and migration whereas inhibition of both genes inhibits angiogenesis. Taken altogether, our findings reveal a novel role for miR-204/ANGPT1/TGFßR2 axis in tumor angiogenesis. We propose that therapeutic manipulation of miR-204 levels may represent a promising approach in breast cancer.


Assuntos
Angiopoietina-1/biossíntese , Neoplasias da Mama/irrigação sanguínea , Neoplasias da Mama/metabolismo , MicroRNAs/biossíntese , Proteínas de Neoplasias/biossíntese , Neovascularização Patológica/metabolismo , Proteínas Serina-Treonina Quinases/biossíntese , RNA Neoplásico/biossíntese , Receptores de Fatores de Crescimento Transformadores beta/biossíntese , Angiopoietina-1/genética , Neoplasias da Mama/genética , Neoplasias da Mama/terapia , Feminino , Humanos , Células MCF-7 , MicroRNAs/genética , Proteínas de Neoplasias/genética , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Neovascularização Patológica/terapia , Proteínas Serina-Treonina Quinases/genética , RNA Neoplásico/genética , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/genética
8.
BMC Cancer ; 16: 379, 2016 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-27377268

RESUMO

BACKGROUND: Aberrant expression of microRNAs has been associated with migration of tumor cells. In this study, we aimed to investigate the biological significance of miR-944 whose function is unknown in breast cancer. METHODS: MiR-944 expression in breast cancer cells and tumors was evaluated by Taqman qRT-PCR assays. Transcriptional profiling of MDA-MB-231 cells expressing miR-944 was performed using DNA microarrays. Cell viability, migration and invasion were assessed by MTT, scratch/wound-healing and transwell chamber assays, respectively. The luciferase reporter assay was used to evaluate targeting of SIAH1, PTP4A1 and PRKCA genes by miR-944. SIAH1 protein levels were measured by Western blot. Silencing of SIAH1 gene was performed by RNA interference using shRNAs. RESULTS: Our data showed that miR-944 expression was severely repressed in clinical specimens and breast cancer cell lines. Suppression of miR-944 levels was independent of hormonal status and metastatic potential of breast cancer cells. Gain-of-function analysis indicated that miR-944 altered the actin cytoskeleton dynamics and impaired cell migration and invasion. Genome-wide transcriptional profiling of MDA-MB-231 cells that ectopically express miR-944 showed that 15 genes involved in migration were significantly repressed. Notably, luciferase reporter assays confirmed the ability of miR-944 to bind the 3´UTR of SIAH1 and PTP4A1 genes, but not PRKCA gene. Congruently, an inverse correlation between miR-944 and SIAH1 protein expression was found in breast cancer cells. Moreover, SIAH1 was upregulated in 75 % of miR-944-deficient breast tumors. Finally, SIAH1 gene silencing by RNA interference significantly impaired cell migration of breast cancer cells. CONCLUSIONS: Our results pointed out that miR-944 is a novel upstream negative regulator of SIAH1 and PTP4A1 genes and provided for the first time evidence for its functional role in migration and invasion of breast cancer cells. They also suggest that miR-944 restoration may represent a potential strategy for breast cancer therapy.


Assuntos
Neoplasias da Mama/genética , Proteínas de Ciclo Celular/genética , Proteínas de Membrana/genética , MicroRNAs/genética , Proteínas Nucleares/genética , Proteínas Tirosina Fosfatases/genética , Ubiquitina-Proteína Ligases/genética , Regiões 3' não Traduzidas , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Células MCF-7 , Proteínas de Membrana/metabolismo , Proteínas Nucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Tirosina Fosfatases/metabolismo , Ubiquitina-Proteína Ligases/metabolismo
9.
Gerontol Geriatr Med ; 2: 2333721416667879, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28913373

RESUMO

Objective: Sarcopenia is among the most deleterious effects of aging. The objective of this study was to analyze the relationship between performance tests and muscular volume over the life span of male and female participants. Method: A correlation study was conducted with healthy individuals (50 males and 47 females) between the ages of 20 and 94; the study group included active older people, sedentary younger people, and young athletes. Muscular volume was determined by tomography and muscular performance (4-meter speed tests [4 MSTs], chair test, and handgrip test), and a correlation analysis between the groups was performed. Results: Sex-related differences were observed between the variables; in males, muscle volume and functional parameters were closely related with age and physical activity, whereas in females, they were not related at all. Conclusion: Male and female muscle volume and performance demonstrate strong differences, which should be considered during clinical evaluations of sarcopenia.

10.
Oncol Rep ; 30(5): 2399-410, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23970382

RESUMO

microRNAs are small non-coding RNAs of ~22 nucleotides that function at post-transcriptional level as negative regulators of gene expression. Aberrant expression of microRNAs could promote uncontrolled proliferation, migration and invasion of human cancer cells. In this study, we analyzed the expression of microRNA-18b (miR-18b) in breast cancer cell lines and in a set of clinical specimens. Our results showed that miR-18b was upregulated in four out of five breast cancer cell lines and also in breast tumors. In order to identify potential gene targets, we carried out transcriptional profiling of MDA-MB-231 breast cancer cells that ectopically expressed miR-18b. Our results showed that 263 genes were significantly modulated in miR-18b-deficient cells (fold change >1.5; P≤0.05). We found that knock-down of miR-18b induced the upregulation of 55 olfactory receptor (OR) genes and nine genes (NLRP7, KLK3, OLFM3, POSTN, MAGED4B, KIR3DL3, CRX, SEMG1 and CEACAM5) with key roles in cell migration and metastasis. Consistently, we found that ectopic inhibition of miR-18b suppressed the migration of two breast cancer cell models in vitro. In conclusion, we have uncovered genes directly or indirectly modulated by miR-18b which may represent potential therapeutic targets in breast cancer. Our data also pointed out a role of miR-18b in migration of breast cancer cells.


Assuntos
Neoplasias da Mama/genética , Movimento Celular/genética , MicroRNAs/genética , Metástase Neoplásica/genética , Neoplasias da Mama/patologia , Proliferação de Células , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Células MCF-7 , Metástase Neoplásica/patologia , Regulação para Cima
11.
PLoS One ; 8(5): e64378, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23724044

RESUMO

The use of chemopreventive natural compounds represents a promising strategy in the search for novel therapeutic agents in cancer. Resveratrol (3,4',5-trans-trihydroxystilbilene) is a dietary polyphenol found in fruits, vegetables and medicinal plants that exhibits chemopreventive and antitumor effects. In this study, we searched for modulated proteins with preventive or therapeutic potential in MCF-7 breast cancer cells exposed to resveratrol. Using two-dimensional electrophoresis we found significant changes (FC >2.0; p≤0.05) in the expression of 16 proteins in resveratrol-treated MCF-7 cells. Six down-regulated proteins were identified by tandem mass spectrometry (ESI-MS/MS) as heat shock protein 27 (HSP27), translationally-controlled tumor protein, peroxiredoxin-6, stress-induced-phosphoprotein-1, pyridoxine-5'-phosphate oxidase-1 and hypoxanthine-guanine phosphoribosyl transferase; whereas one up-regulated protein was identified as triosephosphate isomerase. Particularly, HSP27 overexpression has been associated to apoptosis inhibition and resistance of human cancer cells to therapy. Consistently, we demonstrated that resveratrol induces apoptosis in MCF-7 cells. Apoptosis was associated with a significant increase in mitochondrial permeability transition, cytochrome c release in cytoplasm, and caspases -3 and -9 independent cell death. Then, we evaluated the chemosensitization effect of increasing concentrations of resveratrol in combination with doxorubicin anti-neoplastic agent in vitro. We found that resveratrol effectively sensitize MCF-7 cells to cytotoxic therapy. Next, we evaluated the relevance of HSP27 targeted inhibition in therapy effectiveness. Results evidenced that HSP27 inhibition using RNA interference enhances the cytotoxicity of doxorubicin. In conclusion, our data indicate that resveratrol may improve the therapeutic effects of doxorubicin in part by cell death induction. We propose that potential modulation of HSP27 levels using natural alternative agents, as resveratrol, may be an effective adjuvant in breast cancer therapy.


Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP27/genética , Proteínas de Choque Térmico HSP27/metabolismo , Proteômica , Estilbenos/farmacologia , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Apoptose/efeitos dos fármacos , Apoptose/genética , Sequência de Bases , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Doxorrubicina/farmacologia , Doxorrubicina/uso terapêutico , Feminino , Técnicas de Silenciamento de Genes , Inativação Gênica , Humanos , Células MCF-7 , Proteoma , RNA Interferente Pequeno/química , RNA Interferente Pequeno/genética , Resveratrol , Espectrometria de Massas em Tandem
12.
Int J Oncol ; 41(2): 670-80, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22614840

RESUMO

Breast cancer is the neoplasia with the highest incidence in women worldwide. Proteomics approaches have accelerated the discovery of diagnostic and prognostic biomarkers. Here, we compared the proteomic profiles of breast tumors versus non-tumoral tissues in order to identify modulated proteins, which could represent potential markers associated to clinical features. By two-dimensional electrophoresis, we detected 28 differentially expressed proteins. Among these, 21 proteins were up-regulated and 7 were down-regulated in tumors (p<0.05). Proteins were identified using LC/ESI-MS/MS tandem mass spectrometry. One protein was identified as glyoxalase 1 (GLO1), an enzyme involved in detoxification of methylglyoxal, a cytotoxic product of glycolysis. GLO1 overexpression was confirmed by western blot assays in paired normal and tumor breast tissues in clinical stages I-III, and by immunohistochemistry on tissue microarrays (TMA) comprising a cohort of 98 breast tumors and 20 healthy specimens. Results from TMA demonstrated that GLO1 is overexpressed in 79% of tumors. Interestingly, GLO1 up-regulation correlates with advanced tumor grade (p<0.05). These findings demonstrate the association of GLO1 overexpression with tumor grade and pointed out for additional studies to establish the importance of GLO1 in breast cancer.


Assuntos
Neoplasias da Mama/enzimologia , Carcinoma Ductal de Mama/enzimologia , Expressão Gênica , Lactoilglutationa Liase/metabolismo , Proteoma/metabolismo , Idoso de 80 Anos ou mais , Sequência de Aminoácidos , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Estudos de Casos e Controles , Linhagem Celular Tumoral , Eletroforese em Gel Bidimensional , Feminino , Humanos , Lactoilglutationa Liase/genética , Pessoa de Meia-Idade , Dados de Sequência Molecular , Gradação de Tumores , Fragmentos de Peptídeos/química , Proteômica , Análise Serial de Tecidos
13.
Biochem Biophys Res Commun ; 341(3): 889-94, 2006 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-16442497

RESUMO

SnoN and Ski oncoproteins are co-repressors for Smad proteins and repress TGF-beta-responsive gene expression. The smad7 gene is a TGF-beta target induced by Smad signaling, and its promoter contains the Smad-binding element (SBE) required for a positive regulation by the TGF-beta/Smad pathway. SnoN and Ski co-repressors also bind SBE but regulate negatively smad7 gene. Ski along with Smad4 binds and represses the smad7 promoter, whereas the repression mechanism by SnoN is not clear. Ski and SnoN overexpression inhibits smad7 reporter expression induced through TGF-beta signaling. Using chromatin immunoprecipitation assays, we found that SnoN binds smad7 promoter at the basal condition, whereas after a short TGF-beta treatment for 15-30 min SnoN is downregulated and no longer bound smad7 promoter. Interestingly, after a prolonged TGF-beta treatment SnoN is upregulated and returns to its position on the smad7 promoter, functioning probably as a negative feedback control. Thus, SnoN also seems to regulate negatively the TGF-beta-responsive smad7 gene by binding and repressing its promoter in a similar way to Ski.


Assuntos
Regulação para Baixo , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Repressoras/metabolismo , Proteína Smad7/genética , Linhagem Celular Tumoral , Regulação para Baixo/efeitos dos fármacos , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Ligação Proteica , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/genética , Transdução de Sinais , Fatores de Tempo , Fator de Crescimento Transformador beta/farmacologia
14.
FEBS Lett ; 579(17): 3701-6, 2005 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-15967445

RESUMO

Proteasome pathway regulates TGF-beta signaling; degradation of activated Smad2/3 and receptors turns TGF-beta signal off, while degradation of negative modulators such as Ski and SnoN maintains the signal. We have found that anisomycin is able to downregulate Ski and SnoN via proteasome as TGF-beta does, but through a mechanism independent of Smad activation. The mechanism used by anisomycin to downregulate Ski and SnoN is also independent of MAPK activation and protein synthesis inhibition. TGF-beta signal was the only pathway described causing Ski and SnoN degradation, thus this new effect of anisomycin on endogenous Ski and SnoN proteins suggests alternative processes to downregulate these negative modulators of TGF-beta signaling.


Assuntos
Anisomicina/farmacologia , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Repressoras/metabolismo , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteína Smad7 , Transativadores/genética , Transativadores/metabolismo
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